The Kempsey Shire Council (KSC) has just upgraded their vacuum sewage system transfer pumps. They were using a lobe pump to transfer raw sewage from their vacuum tank to their sewage treatment plant, but the need for continued maintenance on the sewage pumps was causing cost and logistics issues.
The application was virtually the same, in that they have a vacuum tank that draws sewage through a network of sewer lines that are kept under negative pressure by the vacuum tank. When the vacuum tank fills, it needs to be pumped out. Because the tank is under a vacuum (up to -80kPa), the transfer pump needs to be able to pull a “suction lift” equivalent to this, and still be able to produce discharge pressures high enough to transfer sewage to the WWTP (in this case, an additional 60 metres, for a total dynamic head of 68 metres).
After reviewing the system, Hydro Innovations selected the Gorman-Rupp VS3A60-B self priming pump with a 45kW motor. The pump is one of Gorman-Rupp’s Ultra VS Series of two-stage self priming sewage pumps, capable of producing heads to 90 metres. Being a self priming pump, it is more than capable of producing the required vacuum to overcome the negative pressure inside the vacuum tank. This sewage pump comes standard with a self cleaning wear plate system to enable it to handle stringy materials such as rags, has a large open impeller to handle larger solids and has a large removable cover-plate for access into pump internals to remove large blockages or for inspection.
As with all of Gorman-Rupp’s sewage pumps in Australia, internal clearance adjustments are able to be done externally, without exposing operators to sewage or the wet well. These adjustments can be done in minutes, so operators can keep the pumps at peak operating efficiency for the life of the installation.
Ian and a small delegation from KSC went to Bundaberg to investigate and confirm all they had been told about the success at the Woodgate site with the Gorman-Rupp units. After reviewing the installation and discussions with the operators at the Bundaberg Shire Council, they decided to proceed with the purchase of the recommended Gorman-Rupp self priming pumps for the job.